Hi doniphan,
If I am understanding correctly then this can be done a lot easier than you are doing at the moment. What you can do is have two fields in the one weblog and they will be called {summary} and {body} and all you will do is on the page where you wish to show the snippet is use the shorter text that you write into the {summary} field and then on the page where you wish to show the full text you will use the {body} field instead.
Something along these lines :
{exp:weblog:entries weblog="default_site" disable="member_detail|categories|category_fields|trackbacks" dynamic="off"}
<h2>{title}</h2>
<p>{summary}<br />
<a href="http://{url_title_path=site/detail}" title="Read more on - {title}">Read moreā¦</a><br />
{/exp:weblog:entries}
You would then have a template called detail in the site template group (note these can be exchanged for whatever you like though) which would have this code in it :
{exp:weblog:entries weblog="default_site" disable="member_detail|categories|category_fields|trackbacks" dynamic="on"}
<h2>{title}</h2>
<p>{body}<br />
{/exp:weblog:entries}
Hope that helps a bit?
Best wishes,
Mark